"Denis never crossed my mind. He was there under Gerry Adams' tutelage, so he was trusted. He was very affable - not intellectual but smart, in a streetwise way. He was meticulous about his work.

"Denis displayed no excesses in mood or habit. He must have been on big money from his paymasters but he was never flash. He drove a 10-year-old car. He was a thrifty kind of fellow, always counting his pennies."

Four months later, Donaldson (56) was shot dead in a cottage in Donegal. Mystery surrounds his outing as an informer.

He had confessed his role to Sinn Fein after allegedly being visited by police, who warned him that the media was about to expose his double life. But no journalist has ever said they were working on that story. The Police Ombudsman is investigating the matter.

From the Short Strand in east Belfast, Donaldson was imprisoned in the H-Blocks for explosive offences in the 1970s. He was an informer for over 20 years including when he travelled the world as a senior IRA intelligence officer and when he ran the Noraid office in New York.

He was one of three people charged with involvement in an IRA spy-ring at Stormont in 2002. The charges were later dropped.

A 74-year-old man has been charged over withholding information about his murder. An inquest into Donaldson's death has been repeatedly adjourned. A journal he was writing is in the hands of gardai.